1. Field of the Invention
The present invention relates to virtual namespaces for active computing environments.
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2. Background Art
In modern computing it is desirable for a user to be interacting with a computer, to stop the interaction with the computer, to move to a new computer, and to begin interacting with the new computer at precisely the point where the user stopped interacting with the first computer. Using current schemes, however, this is not possible because the user's computing environment cannot be represented in a form that can be understood by both computers and moved between the computers.
However, in co-pending U.S. patent application entitled “Method and Apparatus for Representing and Encapsulating Active Computing Environments” Application No. 09/764,774 filed on Jan. 16, 2001, assigned to the assignee of the present application, and hereby fully incorporated into the present application by reference, it was described how a group of active processes and their associated state could be represented in a form that made it possible to halt the active processes, to move them to a different binary compatible machine, or to suspend them on a disk for later revival on the same or a different machine.
In such an environment, many users may be accessing data or computer programs on a single remote computer. It would be desirable if the users could arrange and organize the appearance of the data and computer programs in a way that is suitable for them. Furthermore, it would be desirable if the user's system interface was virtualized in a manner that allowed for portability. Current schemes, however, do not allow for such customization or virtualization. Before further discussing the drawbacks of current schemes, it is instructive to discuss how the nature of computing is changing.
The Nature of Computing
The nature of computing is changing. Until recently, modem computing was mostly “machine-centric”, where a user accessed a dedicated computer at a single location. The dedicated computer had all the data and computer programs necessary for the user to operate the computer, and ideally, it had large amounts of hardware, such as disk drives, memory, processors, and the like. With the advent of computer networks, however, different computers have become more desirable and the focus of computing has become “service-oriented”. In particular, computer networks allow a user to access data and computer programs that exist elsewhere in the network When the user accesses such data or computer programs, the remote computer is said to be providing a service to the user. With the improvement in services available to users, the need to have a dedicated computer following the machine-centric paradigm is greatly reduced. The machine-centric paradigm also becomes much less practical in this environment because distributing services is much more cost-effective.
In particular, computers in a service-oriented environment have little need for powerful hardware. For instance, the remote computer processes the instructions before providing the service, so a powerful processor is not needed on the local access hardware. Similarly, since the service is providing the data, there is little need to have large capacity disk drives on the local access hardware. In such an environment, one advantage is that computer systems have been implemented that allow a user to access any computer in the system and still use the computer in the same manner (i.e., have access to the same data and computer programs).
For instance, a user may be in location A and running a word processor, a web browser, and an interactive multimedia simulation. In a service-oriented environment, the user might stop using the computer in location A and move to location B where the user could resume these computer programs on a different machine at the exact point where the user stopped using the machine at location A, as long as both computers had access via the computer network to the servers where the programs were being executed. The programs in this example, however, cannot be moved between computers when they are active because of the design of current operating systems.
Resource Naming
On a typical machine object names are host-dependent and not the resource interface between the kernel and user is not cleanly separated. Tokens used by the kernel to identify resources encapsulate the binding to the underlying physical resource as well, and resource tokens are only valid for a specific machine. This creates unnecessary dependencies that irreversibly couple processes to particular instances of an operating system on particular machines
One scheme, for instance, uses a Unix process identifier (PID), which is a token by which one process may refer to another process. The PID, however, is actually an index into an active process table inside the kernel, (i.e., it is the physical resource itself). A PID is only valid on a particular machine and is not globally unique. A process cannot move to another machine and maintain the same PID. Thus, a scheme using a PID limits the ability for a group of active processes to move between machines and still be able to access the resources they need to continue to run.
Customization
It is desirable to retain some of the benefits of machine-centric computing. In particular, machine-centric computing allows a user to customize their computing environment, for instance by arranging and naming their file system. This is trivial in a machine-centric environment because typically only one user controls the machine. In a service-oriented environment, however, remote computers are often accessed by many users, and the same files are shared between all of these users. In such environments, users have little opportunity to customize their environment.
Privacy, Isolation, and Security
Other benefits from machine-centric computing that are desirable to retain are privacy, isolation, and security. In particular, machine centric computing gives the user a dedicated machine that is completely secure and private, and totally isolated from everyone else. In a shared environment, however, such security, privacy, and isolation is difficult to achieve.
In a service-oriented environment remote computers are often accessed by many users, and the same resources are shared between all of these users. In such environments, users can view and sometimes manipulate the resources in use by others. These issues are all related to the naming of resource objects in the system (e.g., files, processors, memory, and attached devices). One scheme, for instance, shares the names of objects across many users. This limits isolation and privacy because every user can name and access all objects in the system, including those controlled by others. This further limits security because every user has access to the same objects and may perform unwanted modifications on them.